Leaning on the original ROM for PRINT/INPUT/FP math is what makes this faithful instead of merely functional, since you inherit the hardware's quirks instead of

Leaning on the original ROM for PRINT/INPUT/FP math is what makes this faithful instead of merely functional, since you inherit the hardware's quirks instead of reimplementing the away. Instruction-level rather than cycle-accurate is also fine here; nobody's timing-attacking a 921 kHz BASIC pocket calc.